This invention relates to air compressors of the rotary type and air cooling systems employing such compressors. In particular, this invention relates to an air cooling system which utilizes a rotary air compressor and air as a coolant. of
Compressors generally are of either the reciprocal or centrifugal type. Reciprocal type compressors require a number of reciprocating pistons and a valving arrangement for allowing entry and exit of air. The entire configuration is substantially similar to that is an internal combustion engine. Because of the greater number and complexity of parts of this type of compressor is subject to a great deal of wear, and a high breakdown rate. Additionally the number and interaction of parts results in a unit that is relatively inefficient in terms of power consumption and quite noisy.
Rotary type compressors require fewer parts but their compression efficiency is generally low because of the lack of frictional engagement between the impellers and the housing. In order to increase the compression efficiency the impellers must either be rotated at an extremely high revolution rate, or the impellers must frictionally engage the housing walls. As noted subsequently with regard to prior air cooling systems employing rotary compressors, prior rotary compressors where the compellers or vanes engaged the wall have a short life and high maintenance costs.
Air cooling systems generally comprise compressors for compressing a coolant such as Freon. Heat is removed from the compressed Freon by a heat exchanger. The compressed Freon is allowed to expand, and circulate in cooling coils. In such systems the Freon must be maintained in a closed fluid system so that leakage of the Freon is a problem. Because the efficiency of these systems is low, they consume a great deal of energy. Refrigerating systems of the type described tend to extract moisture from the air. This is undesirable because food cooled by such a system tends to dehydrate which can adversely affect the food product being cooled. These systems also have many moving parts which can increase maintenance costs due to the wear and tear of these parts, and resulted in a noisy system.
A rotary, open loop, air cooling system which utilizes air as the coolant has been developed to overcome the disadvantages of the closed fluid cooling systems. See "An Air Conditioner That Doesn't Need Freon", in Business Week, Aug. 25, 1973, p. 30. The rotary air conditioner described in the above mentioned publication comprises a rotor fitted with a plurality of sliding vanes. The rotor is contained in an elliptical housing. As the rotor turns, the sliding vanes slide radially in and out to adjust the elliptically varying wall configuration of the housing. Fresh air is sucked into the housing by the rotation of the rotor. The air is trapped and compressed in the decreasing space between the vanes. As the air is compressed, it heats up to a temperature of approximately 250.degree. F. The air then is allowed to pass through a heat exchanger where it cools to ambient temperature while still remaining in a compressed state. The rotor is continually rotating and once the air has been compressed, the vanes slide radially outward to provide an increasingly larger cavity. The cool compressed air is coupled into this expanding cavity where the air expands and cools to a temperature of below 0.degree. F.
The rotary air conditioner described above has some basic disadvantages. The sliding vanes wear as they slide back and forth in their slots. As a result, leakage occurs between cavities of the sliding vanes and the efficiency of the unit is reduced. Accordingly, the maintenance costs increase and the life expectancy decreases. Noise is also a problem due to the large number of moving parts.
A rotary engine, of the type described in U.S. Pat. No. 3,297,006, by J. W. Marshall entitled "Rotary Pumps and Engines", provides an inherently balanced engine which is very quiet and has very few moving parts. As will be shown, the structure of the rotary engine is modified according to the invention to provide an air cooling system which overcomes many of the disadvantages heretofore known in prior art air cooling systems.